Improve metrics for builds that fail

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [Unreleased]
 
+- Improved buildpack metrics for builds that fail. ([#1746](https://github.com/heroku/heroku-buildpack-python/pull/1746))
 
 ## [v276] - 2025-02-05
 

bin/report

@@ -62,6 +62,7 @@ kv_pair_string() {
 STRING_FIELDS=(
 	cache_status
 	django_collectstatic
+	failure_detail
 	failure_reason
 	nltk_downloader
 	package_manager

bin/steps/python

@@ -23,6 +23,7 @@ if ! curl --output /dev/null --silent --head --fail --retry 3 --retry-connrefuse
 		https://devcenter.heroku.com/articles/python-support#supported-python-versions
 	EOF
 	meta_set "failure_reason" "python-version-not-found"
+	meta_set "failure_detail" "${python_full_version}"
 	exit 1
 fi
 
@@ -42,6 +43,7 @@ else
 			Please try again and to see if the error resolves itself.
 		EOF
 		meta_set "failure_reason" "python-download"
+		# TODO: Set failure_detail here once refactored.
 		exit 1
 	fi
 

lib/checks.sh

@@ -20,6 +20,7 @@ function checks::ensure_supported_stack() {
 				Upgrade to a newer stack to continue using this buildpack.
 			EOF
 			meta_set "failure_reason" "stack::eol"
+			meta_set "failure_detail" "${stack}"
 			exit 1
 			;;
 		*)
@@ -34,6 +35,7 @@ function checks::ensure_supported_stack() {
 				https://devcenter.heroku.com/articles/managing-buildpacks#classic-buildpacks-references
 			EOF
 			meta_set "failure_reason" "stack::unknown"
+			meta_set "failure_detail" "${stack}"
 			exit 1
 			;;
 	esac

lib/kvstore.sh

@@ -23,8 +23,20 @@ kv_set() {
 	# TODO: Stop ignoring an incorrect number of passed arguments.
 	if [[ $# -eq 3 ]]; then
 		local f="${1}"
+		local key="${2}"
+
+		# Truncate the value to an arbitrary 100 characters since it will sometimes contain user-provided
+		# inputs which may be unbounded in size. Ideally individual call sites will perform more aggressive
+		# truncation themselves based on the expected value size, however this is here as a fallback.
+		# (Honeycomb supports string fields up to 64KB in size, however, it's not worth filling up the
+		# metadata store or bloating the payload passed back to Vacuole/submitted to Honeycomb given the
+		# extra content in those cases is not normally useful.)
+		local value="${3:0:100}"
+		# Replace newlines since the data store file format requires that keys don't span multiple lines.
+		value="${value//$'\n'/ }"
+
 		if [[ -f "${f}" ]]; then
-			echo "${2}=${3}" >>"${f}"
+			echo "${key}=${value}" >>"${f}"
 		fi
 	fi
 }

lib/python_version.sh

@@ -104,7 +104,7 @@ function python_version::parse_runtime_txt() {
 			in the correct format.
 
 			The following file contents were found, which aren't valid:
-			${contents}
+			${contents:0:100}
 
 			However, the runtime.txt file is deprecated since it has
 			been replaced by the .python-version file. As such, we
@@ -125,6 +125,7 @@ function python_version::parse_runtime_txt() {
 			your app to receive Python security updates.
 		EOF
 		meta_set "failure_reason" "runtime-txt::invalid-version"
+		meta_set "failure_detail" "${contents:0:50}"
 		exit 1
 	fi
 }
@@ -174,6 +175,7 @@ function python_version::parse_python_version_file() {
 					your app to receive Python security updates.
 				EOF
 				meta_set "failure_reason" "python-version-file::invalid-version"
+				meta_set "failure_detail" "${line:0:50}"
 				exit 1
 			fi
 			;;
@@ -193,17 +195,19 @@ function python_version::parse_python_version_file() {
 				begin with a '#', otherwise it will be treated as a comment.
 			EOF
 			meta_set "failure_reason" "python-version-file::no-version"
+			meta_set "failure_detail" "${contents:0:50}"
 			exit 1
 			;;
 		*)
+			local first_five_version_lines=("${version_lines[@]:0:5}")
 			output::error <<-EOF
 				Error: Invalid Python version in .python-version.
 
 				Multiple versions were found in your .python-version file:
 
 				$(
 					IFS=$'\n'
-					echo "${version_lines[*]}"
+					echo "${first_five_version_lines[*]}"
 				)
 
 				Update the file so it contains only one Python version.
@@ -212,6 +216,10 @@ function python_version::parse_python_version_file() {
 				lines begin with a '#', so that they are ignored.
 			EOF
 			meta_set "failure_reason" "python-version-file::multiple-versions"
+			meta_set "failure_detail" "$(
+				IFS=,
+				echo "${first_five_version_lines[*]}"
+			)"
 			exit 1
 			;;
 	esac
@@ -233,17 +241,19 @@ function python_version::read_pipenv_python_version() {
 	fi
 
 	if ! version=$(jq --raw-output '._meta.requires.python_full_version // ._meta.requires.python_version' "${pipfile_lock_path}" 2>&1); then
+		local jq_error_message="${version}"
 		output::error <<-EOF
 			Error: Can't parse Pipfile.lock.
 
 			A Pipfile.lock file was found, however, it couldn't be parsed:
-			${version}
+			${jq_error_message}
 
 			This is likely due to it not being valid JSON.
 
 			Run 'pipenv lock' to regenerate/fix the lockfile.
 		EOF
 		meta_set "failure_reason" "pipfile-lock::invalid-json"
+		meta_set "failure_detail" "${jq_error_message:0:100}"
 		exit 1
 	fi
 
@@ -282,6 +292,7 @@ function python_version::read_pipenv_python_version() {
 			https://pipenv.pypa.io/en/stable/specifiers.html#specifying-versions-of-python
 		EOF
 		meta_set "failure_reason" "pipfile-lock::invalid-version"
+		meta_set "failure_detail" "${version:0:50}"
 		exit 1
 	fi
 }
@@ -341,6 +352,7 @@ function python_version::resolve_python_version() {
 			EOF
 		fi
 		meta_set "failure_reason" "python-version::eol"
+		meta_set "failure_detail" "${major}.${minor}"
 		exit 1
 	fi
 
@@ -388,6 +400,7 @@ function python_version::resolve_python_version() {
 			EOF
 		fi
 		meta_set "failure_reason" "python-version::unknown-major"
+		meta_set "failure_detail" "${major}.${minor}"
 		exit 1
 	fi
 

lib/utils.sh

@@ -48,10 +48,12 @@ function utils::bundled_pip_module_path() {
 }
 
 function utils::abort_internal_error() {
-	local message="${1}"
+	local message
+	message="${1} (line $(caller || true))"
 	output::error <<-EOF
-		Internal error: ${message} (line $(caller || true)).
+		Internal error: ${message}.
 	EOF
 	meta_set "failure_reason" "internal-error"
+	meta_set "failure_detail" "${message}"
 	exit 1
 }